2024-03-29T10:02:35Zhttps://repositori.uji.es/oai/requestoai:repositori.uji.es:10234/135732023-05-16T08:44:00Zcom_10234_7013com_10234_9col_10234_8638
00925njm 22002777a 4500
dc
Polo Ortiz, Victoriano
author
González Navarrete, Patricio
author
Silvi, Bernard
author
Andres, Juan
author
2008
A set of four reactions, XCH3+X− (X=F, Cl, Br)
and ClSiH3+Cl−, is investigated by means of the joint use of
the electron localization function (ELF) and catastrophe theory
(CT) analysis in order to obtain newinsights into the bond
breaking/forming processes for identity SN2 gas-phase reactions.
Using DFT calculations at the OLYP/6-311++G(d,p)
level, the effect of nucleophile (F, Cl, and Br anions) and the
role of reacting centers (C or Si) on the reaction mechanisms
are investigated. The charge-shift character of carbon–halogen
bonds is studied by determination of the weights of the
Lewis resonance structures. In all SN2 reactions at the carbon
atom, there is a progressive reduction on the covalent character
of the C–X bond from the reactant complex (0.41, 0.57,
0.58 for F, Cl, and Br, respectively) until the bond-breaking
process, occurring before the transition structure is reached.
On the other hand, the Si–Cl bond maintains its degree of
covalent character (0.51) from the isolated fragments to the
formation of a stable transition complex, presenting two silicon–
chlorine charge-shifted bonds. The analysis of the ELF
topology along the reaction path reveals that all reactions proceed
via the same turning points of fold-type but the order is
inverted for reactions taking place at C or Si atoms
1432881X
http://hdl.handle.net/10234/13573
Electron localization function (ELF)
Catastrophe theory
DFT calculations
SN2 reactions
Methyl transfer reactions
An electron localization function and catastrophe theory analysis on the molecular mechanism of gas-phase identity SN2 reactions